Question about Logitech MX Master 3S

This only works via the Bolt receiver.

This is not compatible with Unify receivers, I totally fell for it, well now I use it via the normal bluetooth from the laptop.

Unfortunately no, it only works with the Bolt receiver, not with the Unifying receiver. No receiver is included in the scope of delivery. So either you already have a Bolt receiver (which can connect multiple devices) or you order one separately.☹️